Effects of polysulfated glycosaminoglycan and triamcinolone acetonid on the production of proteinases and their inhibitors by IL-1α treated articular chondrocytes

Abstract

In this study we determined the in vitro effects of polysulfated glycosaminoglycan (PSGAG) and the glucocorticoid triamcinolone acetonid (TA) on the IL-1 altered expression and activity of matrix metalloproteinases (MMP-1, MMP-3), tissue inhibitor of metalloproteinases-1, the plasminogen activators tPA and uPA and plasminogen activator inhibitor 1 by articular chondrocytes. Bovine chondrocytes were cultured in alginate gel beads. Cells were treated with interleukin-1α (IL-1α) in the presence of vehicle or drugs at various concentrations. After 48 hr mRNA expression of MMP-1, MMP-3, TIMP-1, uPA, tPA and PAI-1 was analyzed by RT-PCR-ELISA. The protein synthesis of TIMP-1 and MMP-3 was determined by immunoprecipitation, PAI-1 protein was quantitated by ELISA. The activity of enzymes and inhibitors was measured by functional assays. Treating chondrocytes with IL-1 induced the expression of MMPs and downregulated TIMP-1 but stimulated both the expression of PAs and PAI-1. Both drugs significantly reduced collagenase and proteoglycanase activities which was accompanied by inhibition of the expression of MMP-1 and MMP-3. The IL-1 decreased expression of TIMP-1 was further reduced by TA, which resulted in a significant loss of TIMP activity. No effects on TIMP activity or TIMP-1 biosynthesis were observed after treatment of chondrocytes with PSGAG. Both drugs inhibited the IL-1-induced mRNA expression of tPA, whereas expression of uPA was only mildly reduced by PSGAG, which also induced PAI-1 above IL-1 stimulated levels. As inhibition of collagenase activities and tPA expression by PSGAG occured at physiological concentrations it might be of clinical relevance, indicating that PSGAG could help reducing cartilage degradation and has a strong anti-fibrinolytic potential. Due to their co-regulation of MMPs and TIMP(s) glucocorticoids should be carefully studied for their overall effect on extracellular matrix proteolysis.